Dyeing and printing textile materials made of cellulose fibers

ABSTRACT

A process for dyeing and printing textile materials consisting of cellulose fibers or containing cellulose fibers in a blend with other fibers in an aqueous medium at above pH 12 with vattable dyes in the presence of cyclic compounds which contain at least one instance of the structural unit ##STR1## in the ring of the molecule as reducing agents and finishing the dyeing in a conventional manner.

The present invention relates to a process for dyeing and printingtextile materials consisting of cellulose fibers or containing cellulosefibers in a blend with other fibers in an aqueous medium at above pH 12with vattable dyes in the presence of at least one reducing agent forthe vattable dyes and finishing the dyeing in a conventional manner.

EP-A-0 364 752 discloses a process for dyeing textile materials made ofcellulose fibers with vat dyes in an alkaline medium, wherein thereducing agents used are mixtures of sodium dithionite and/or thioureadioxide and α-hydroxycarbonyl compounds, such as hydroxyacetone, and thedyeing is carried out at a pH of not less than 13 and at temperaturesabove 75° C. The dyeing is then finished in a conventional manner byoxidizing and washing the dyed material. The α-hydroxycarbonyl compoundsdescribed therein, such as hydroxyacetone, are not sufficiently stableunder the dyeing conditions, being converted in an unpredictable mannerinto a multiplicity of products which inter alia lead to odor problems.The use of sodium dithionite and/or thiourea dioxide as reducing agentsin the dyeing of cellulose fibers with vat dyes causes sulfite andsulfate ion pollution in the production waste waters of dyehouses.

It is an object of the present invention to provide a reducing agent forthe above-described process which is stable in the strongly alkalinedyeing liquor, i.e. which does not condense to form colored productsunder the dyeing conditions and ideally causes no odor problems.

We have found that this object is achieved by a process for dyeing andprinting textile materials consisting of cellulose fibers or containingcellulose fibers in a blend with other fibers in an aqueous medium atabove pH 12 with vattable dyes in the presence of at least one reducingagent for the vattable dyes and finishing the dyeing in a conventionalmanner, wherein the reducing agents used are cyclic compounds whichcontain at least one instance of the structural unit ##STR2## in thering of the molecule.

Surprisingly, cyclic α-hydroxyketones that contain structure I give ahigher color yield than hydroxyacetone. A further decisive advantageover hydroxyacetone is that the cyclic α-hydroxyketones that containstructure I in the ring of the molecule do not develop a troublesomeodor in dyeing and, owing to their stability in the alkaline pH range,do not turn the liquor brown.

The textile materials consist of cellulose fibers or contain cellulosefibers in a blend with other fibers. They can be in any state ofprocessing, for example in the form of loose fiber, card sliver, yarn onpackage, yarn as hank, woven fabric or knitted fabric. The cellulosefibers can be either natural or regenerated cellulose, such as stapleviscose, filament viscose or polynosics. The process of the inventioncan be used for dyeing not only mercerized cotton but also raw cottonand also raw yarn on package or as hank. Synthetic fibers present in thetextile materials in a blend with the cellulose fibers are for examplepolyester fibers, polyacrylonitrile fibers or synthetic polyamidefibers.

The cellulose fibers are dyed with vattable dyes, such as vat dyes, inparticular indigo, or sulfur dyes. The vat dyes are either indigo oranthraquinonoid or indigoid dyes. Vat dyes and sulfur dyes have longbeen commercially available and are documented in the Colour Index(C.I.); cf. Colour Index, 3rd edition 1971, Volume 3, pages 3719 to3844, and Volume 4, C.I. Nos. 58000 to 74000, Soc. Dyers and Colourists,England.

The vattable dyes are used in the process of the invention in theamounts hitherto customary for dyeing, for example within the range from0.01 to 10% by weight, based on the textile material. It is possible touse a single dye or a mixture of two or more vattable dyes. The dyeingof the textile materials can take place by the exhaust method, forexample from a long aqueous liquor at a liquor ratio of from 5:1 to40:1, preferably from 8:1 to 20:1, or else in a continuous process, forexample by the pad-steam process. In this case the liquor ratio usedranges from 0.5:1 to 3:1 and correspondingly higher concentrations ofreducing agent and sodium hydroxide are used, usually from 10 to 100 g/lof at least one reducing agent and from 50 to 200 g/l of 38° Be NaOH.Printing of the textile materials by the process of the invention ispossible too.

The pH of the aqueous liquor is above 12. It is set by adding an alkalimetal hydroxide to the aqueous dyeing medium. Suitable alkali metalhydroxides are sodium hydroxide and potassium hydroxide, the use ofsodium hydroxide being preferred. The concentration of alkali metalhydroxide in the aqueous dyeing liquor is customarily in the range from10 to 500, preferably from 30 to 250, ml of aqueous 38° Be alkali metalhydroxide solution/l of liquor.

To dye cellulose fibers with vattable dyes, the dyes have to beconverted into the leuco form. This is done using a reducing agent whichaccording to the invention is a cyclic compound containing at least oneinstance of the structural unit ##STR3## in the ring of the molecule.This kind of compound is essentially a carbocyclic compound having from6 to 12, preferably from 6 to 8, carbon atoms in the ring, or asaturated α-hydroxycyclopentanone. The cyclic compounds having at least6 carbon atoms in the ring may contain a double bond or a fused-onaromatic substituent. Examples of suitable compounds having thestructural unit (I) in the ring of the molecule are the followingcompounds:

In the formulae I-XV the hydrogen atoms on the carbocyclic ring have forclarity been omitted. ##STR4## where the substituents R¹, R², R³ and R⁴are independently of one another H, C₁ -C₄ -alkyl, OH, OCH₃ or phenyl,for example the compounds IIa to IId: ##STR5## where the substituentsR¹, R², R³ and R⁴ are each as defined in the formula II, for example thecompounds IIIa-IIIc: ##STR6## where n is 1 or 2, ##STR7## where thesubstituents R¹, R² and R³ are independently of one another H, C₁ -C₄-alkyl, OH, OCH₃ or phenyl, for example the compounds Va-Vc: ##STR8##where the substituents R¹, R² and R³ are independently of one another H,C₁ -C₄ -alkyl, OH or OCH₃, for example the compounds VIa-VIc: ##STR9##and also the compounds VII-XV: ##STR10##

Of the above-indicated cyclic α-hydroxyketones containing the structuralunits I, α-hydroxycyclohexanone and α-hydroxycyclopentanone arepreferred. Depending on the dye concentration in the dyebath, the cyclicα-hydroxyketones containing the structural unit I are used in amounts offrom 0.5 to 10, preferably from 1 to 6, g/l.

To speed up the dyeing process, it has proven advantageous in some casesto carry out the dyeing or printing in the additional presence ofquinonoid compounds which are water-soluble at above pH 12. Under thedyeing conditions these compounds are present in the aqueous liquor in astate of solution. Suitable quinonoid compounds for this purpose areknown from DE-B-2 164 463. Quinonoid compounds are for examplehydroxyl-, carboxyl- and/or sulfo-containing derivatives ofbenzoquinone, of naphthoquinone, of acenaphthenequinone or ofanthraquinone, such as hydroxyanthraquinones, e.g.2-hydroxyanthraquinone and 1,4-dihydroxyanthraquinone,anthraquinonecarboxylic acids and anthraquinonesulfonic acids, such asanthraquinone-2-sulfonic acid and 1,4-diaminoanthraquinone-2-sulfonicacid. These compounds are customary for use as accelerants in vatdyeing. The quinonoid compounds are used in amounts of from 1 to 10% byweight, based on the amount of dye used.

The cyclic α-hydroxyketones that contain structure I can if desired beused together with any reducing agent known for the dyeing of vat dyes,for example in a mixture with sodium dithionite and/or thiourea dioxide.The weight ratio of cyclic α-hydroxyketones to be employed according tothe invention to sodium dithionite and/or thiourea dioxide in suchreducing agent mixtures is for example from 1:1 to 1:15, preferably from1:2 to 1:10.

The alkaline aqueous dyeing liquor, in addition to at least one vattabledye and one or more cyclic α-hydroxyketones that contain structuralunits I, may contain polymers of monoethylenically unsaturatedcarboxylic acids as dyeing assistants. Such dyeing assistants are knownfor example from DE-B-2 444 823. They are essentially homo- andcopolymers of monoethylenically unsaturated carboxylic acids. Thecopolymers contain at least 10% by weight of a monoethylenicallyunsaturated carboxylic acid in the form of copolymerized units.Individual compounds of this kind are for example polyacrylic acid,polymethacrylic acid, copolymers of acrylic acid or methacrylic acidwith other monomers, for example methacrylamide, acrylamide,acrylonitrile, methacrylonitrile, acrylic esters or methacrylic esters.It is also possible to use copolymers of acrylic acid and maleic acid,copolymers of acrylic acid and itaconic acid, copolymers of maleic acidand vinyl esters, copolymers of maleic acid and vinyl ethers. The onlyessential requirement is that the copolymers should contain at least 10,preferably at least 50, mol % of a monoethylenically unsaturatedcarboxylic acid in the form of copolymerized units. The copolymers canbe used as dyeing assistants in the form of the free acids or preferablyalready neutralized with alkalis. The K values of the homo- andcopolymers of monoethylenically unsaturated carboxylic acids range from15 to 90, preferably from 20 to 65. The K values are determined by themethod of H. Fikentscher, Cellulosechemie 13 (1932), 58-64, 71-74, on a1% strength by weight aqueous solution of the sodium salt at 25° C. andpH 7. The polymers are used in amounts of from 0.05 to 2% by weight,based on the textile materials to be dyed.

The dyeing is carried out within the temperature range within which itis customary to carry out vat dyeings using reducing agents, for examplewithin the range from 20° to 130° C., preferably from 40° to 115° C. Iftemperatures above the boiling point of the liquor are employed, thedyeing is carried out in conventional pressure apparatus such as HTapparatus, jet dyeing machines, etc. in accordance with the makeup formof the textile material.

The textile material, which following the treatment in the dyebathcontains the vatted dye in the leuco form, is treated in a conventionalmanner to finish the dyeing. To this end the textile material is firstoxidized in a conventional manner of vat dyeing, for example by exposingthe leucodye-containing material to the air or treating the materialwith an aqueous liquor which contains hydrogen peroxide or some otheroxidizing agent. After oxidation the dyed textile material is rinsed andsoaped. However, the dyeing can also be finished by first rinsing thetextile material which contains the vat dye in the leuco form, thenoxidizing and then soaping. Soaping is customarily effected using anaqueous solution of a wetting agent with or without sodium carbonate.The dyeings obtained are rub- and wash-fast, and the dyehouse wastewater is not contaminated with sulfate or sulfite ions.

EXAMPLES Example 1

A bleached cotton tricot is dyed in a laboratory beaker bath in a liquorratio of 20:1 with a liquor containing per liter 0.5 g of the blue vatdye of C.I. No. 69825, 30 ml of 38° Be sodium hydroxide solution and 3 gof α-hydroxycyclohexanone. The dyeing vessel is introduced into the bathat 25° C. and heated over 15 min to 60° C. The cotton tricot is thendyed at 60° C. for 30 min. It is then removed from the dyebath andfinished in a conventional manner by oxidizing, rinsing and soaping. Theblue dyeing obtained is level and rub- and wash-fast.

Example 2

A bleached cotton tricot is dyed in a laboratory beaker bath in a liquorratio of 20:1 with a liquor containing per liter 0.5 g of the green vatdye of C.I. No. 59825, 30 ml of 38° Be sodium hydroxide solution and 3 gof α-hydroxycyclohexanone. The dyeing vessel is introduced into the bathat 25° C. and heated over 15 min to 60° C. as described in Example 1.The dyeing of the textile material is carried out at 60° C. over 30 min.The cotton tricot is then removed from the dyebath and finished in aconventional manner by oxidizing, rinsing and soaping. The green dyeingobtained is level and rub- and washfast. Its depth of shade correspondsto that of a comparative dyeing obtained by the known IN method bydyeing the same material with a dyeing liquor containing per liter 18 mlof 38° Be sodium hydroxide solution and 6 g of sodium dithionite at 60°C. for 45 min.

Comparative Example 1

A bleached cotton tricot is dyed in a laboratory beaker bath in a liquorratio of 20:1 with the dyeing liquor containing per liter 0.5 g of theblue vat dye of C.I. No. 69825, 30 ml of 38° Be sodium hydroxidesolution and 3 g of hydroxyacetone. The dyeing was carried out under theconditions specified in Example 1. The result obtained was a level, rub-and wash-fast blue dyeing which was about 40% weaker than that obtainedin Example 1.

Comparative Example 2

Example 2 was repeated replacing the α-hydroxycyclohexanone reducingagent with 3 g of hydroxyacetone/l of liquor. The result obtained was alevel, rub- and washfast green dyeing which was about 50% weaker thanthat obtained in Example 2.

Example 3

A bleached cotton tricot is dyed in a laboratory beaker bath in a liquorratio of 20:1 with a liquor containing per liter 0.5 g of the blue vatdye of C.I. No. 60015 (Vat Blue 26), 30 ml of 38° Be sodium hydroxidesolution and 3 g of α-hydroxycyclopentanone. The dyeing vessel isintroduced into the bath at 25° C. and heated over 15 min to 60° C. Thecotton tricot is then dyed at 60° C. for 30 min. The dyeing is thenfinished in a conventional manner by oxidizing, rinsing and soaping. Theblue dyeing obtained is level and rub- and wash-fast. Its depth of shadecorresponds to that of a comparative dyeing obtained with a liquorcontaining per liter 18 ml of 38° Be NaOH and 6 g of sodium dithionite.

Comparative Example 3

Example 3 is repeated with a dyeing liquor containing per liter 0.5 g ofthe blue vat dye of C.I. No. 60015 (Vat Blue 26), 30 ml of 38° Be NaOHand 3 g of hydroxyacetone. The result obtained is a level, rub- andwash-fast blue dyeing which is about 50% weaker than that obtained inExample 3.

Example 4

A bleached cotton tricot is dyed in a laboratory beaker bath in a liquorratio of 20:1 with a liquor containing per liter 0.5 g of the vat dye ofC.I. No. 69525 (Vat Black 25), 30 ml of 38° Be NaOH and 3 g ofα-hydroxycyclopentanone. The dyeing vessel is introduced into the bathat 25° C. and heated over 15 min to 60° C. The material is then dyed at60° C. for 30 min and the dyeing is subsequently finished in aconventional manner by oxidizing, rinsing and soaping. The resultobtained is a level, rub- and wash-fast olive dyeing. Its depth of shadecorresponds to that of a comparative dyeing obtained with a dyeingliquor containing per liter 18 ml of 38° Be NaOH and 6 g of sodiumdithionite.

Comparative Example 4

Example 4 is repeated with the α-hydroxycyclopentanone replaced byhydroxyacetone. This gives a level rub- and wash-fast olive dyeing whichis about 25% weaker than that obtained in Example 4.

Example 5

Bleached cotton twill is impregnated at room temperature to a wet pickupof 70% with a liquor containing per liter 60 g of the green vat dye ofC.I. No. 59825 (Vat Green 01), 2 g of a wetting agent (mixture of mono-,di- and triphosphoric esters of 2-ethylhexanol) and 10 g of anantimigrant (polyacrylamide) and dried at 130° C. for 10 min. Thereafterthe textile material is impregnated at room temperature to 100% of itsweight with a liquor containing per liter 30 g ofα-hydroxycyclopentanone and 100 ml of 38° Be NaOH and then treated at102° C. in a steamer for 1 minute. This is followed by rinsing with coldwater, oxidizing with 3 ml/l of hydrogen peroxide for 3 min, rinsing andsoaping at 98° C. for 5 min. The result is a level, rub- and wash-fastgreen dyeing. Its depth of shade corresponds to that of a comparativedyeing by the customary continuous process with a liquor containing perliter 100 ml of 38° Be NaOH and 60 g of sodium dithionite.

Comparative Example 5

Example 5 is repeated with the α-hydroxycyclopentanone in the reducingagent liquor replaced by hydroxyacetone. The result obtained is a level,rub- and wash-fast green dyeing which is about 25% weaker than thatobtained in Example 5.

Example 6

Bleached cotton twill is impregnated at room temperature to a wet pickupof 70% with a liquor containing per liter 60 g of the blue vat dye ofC.I. No. 69800 (Vat Blue 04), 2 g of a wetting agent (mixture of mono-,di- and triphosphoric esters of 2-ethylhexanol) and 10 g of anantimigrant (polyacrylamide) and dried at 130° C. for 2.5 min.Thereafter the textile material is impregnated at room temperature to100% of its weight with a liquor containing per liter 30 g ofα-hydroxycyclopentanone and 100 ml of 38° Be NaOH and treated at 102° C.in a steamer for 1 min. This is followed by rinsing with cold water,oxidizing with 3 ml/l of hydrogen peroxide for 3 min, rinsing andsoaping at 98° C. for 5 min. The result is a level, rub- and wash-fastblue dyeing. Its depth of shade corresponds to that of a comparativedyeing in which the reduction of the vat dye is carried out with aliquor containing per liter 100 ml of 38° Be NaOH and 60 g of sodiumdithionite.

Comparative Example 6

Example 6 is repeated with the α-hydroxycyclopentanone in the chemicalliquor replaced by hydroxyacetone. The result obtained is a level, rub-and wash-fast blue dyeing which is about 30% weaker than that obtainedin Example 6.

We claim:
 1. A process for dyeing and printing textile materialsconsisting of cellulose fibers or containing cellulose fibers in a blendwith other fibers in an aqueous medium at above pH 12 with vattable dyesin the presence of at least one reducing agent for the vattable dyes andfinishing the dyeing in a conventional manner, which comprises usingreducing agents that are aliphatically saturated cyclic compounds whichcontain at least one instance of the structural unit ##STR11## in thering of the molecule.
 2. A process as claimed in claim 1, wherein thecyclic compounds are used in amounts of from 1 to 10 g/l of liquor.
 3. Aprocess as claimed in claim 1 or 2, wherein the reducing agent used isα-hydroxycyclohexanone.
 4. A process as claimed in claim 1 or 2, whereinthe reducing agent used is α-hydroxycyclopentanone.
 5. A process asclaimed in claim 1, wherein the cyclic compounds are of the formulae(II), (IV), (V), (VI), (VII), (VIII), (X), (XI), (XII), (XIII), (XIV) or(XV): ##STR12## where the substituents R¹, R², R³ and R⁴ areindependently of one another H, C₁ -C₄ -alkyl, OH, OCH₃ or phenyl,##STR13## where n is 1 or 2, ##STR14## where the substituents R⁵, R⁶ andR⁷ are independently of one another H, C₁ -C₄ -alkyl, OH, OCH₃ orphenyl, ##STR15## where the substituents R⁸, R⁹ and R¹⁰ areindependently of one another H, C₁ -C₄ -alkyl, OH or OCH₃, ##STR16## 6.A process for dyeing and printing textile materials consisting ofcellulose fibers or containing cellulose fibers in a blend with otherfibers in an aqueous medium at above pH 12 with vattable dyes in thepresence of at least one reducing agent for the vattable dyes andfinishing the dyeing in a conventional manner, which comprises usingreducing agents that are cyclic compounds of the formulae (IIIa),(IIIb), (IIIc) or (IX): ##STR17##
 7. A process as claimed in any ofclaims 1, 2, 5 or 6, wherein the dyeing is carried out in the additionalpresence of quinonoid compounds which are water-soluble under the dyeingconditions.